proteins

• are Proteins organic or inorganic compounds?

  Organic compounds
• elements found in proteins

  carbon, hydrogen, oxygen, nitrogen.

  often sulphur, phosphorus and iron depending on the type of protein
• what are the monomers of proteins?

  Amino Acids
• how many types of amino acids that occur naturally are there?

  20
• what are Amino Acids made up of?


  they have a NH2 (amino) and COOH (acid) group
• larger molecules of proteins

  dipeptides, tripeptides, polypeptides, proteins
• what are dipeptides?


  2 amino acids joined together with a peptide bond
• what are tripeptides?


  3 amino acids joined together with a peptide bond
• what are polypeptides?


  4 - 49 amino acids joined together with peptide bonds
• how many amino acids does a protein have?

  50 or more
• are proteins soluble in water

  no they are insoluble
• give 1 property of proteins


  they are very sensitive to pH levels and extreme temperatures
• what is the chemical test for proteins?

  biuret test
• explain the biuret test


  sodium hydroxide (NaOH) and copper sulphate (CuSO4) - pale blue colour. add the test substance and heat in a warm water bath for a few minutes. dark purple = proteins present, blue = nothing, rose pink = polypeptides
• biological importance of proteins

  -reserve energy store

  -enzyme are proteins ( control body functions and processes)

  -some hormones are proteins

  -movement - muscles are made of proteins

  -major components of skin, muscle, hair, nails, antibodies and haemoglobin

  -haemoglobin is important in the transport of oxygen (RBCs)
• what are enzymes?


  enzymes are biological, organic catalysts that speed up chemical reactions
• enzymes are very specific and only speed up their own reactions
• are enzymes only one time use


  the body can use them over an dover again, they are not used up or changed in a reaction and only required in small amounts
• what is optimum temperature?

  enzymes work best at optimum temperature, (37 in human body)
• how does temperature effect enzyme activity


  enzyme activity slows down at low temperatures and become inactive or denature in high temperatures
• how do enzymes catalyse chemical reactions?


  begins with the binding of the subtrate (or subtrates) to the active site on the enzyme
• what is the active site?

  the specific region of the enzyme which combines with the substrate
• explain the lock and key analogy


  the lock is the enzyme and the key is the subtrate, only the correct key(subtrate) fits into the key hole (active site) of the lock (enzyme)
• enzymes can split macro-molecules into smaller molecules (monomers)
• enzymes can make bigger molecules from smaller molecules
• examples of everyday uses of enzymes


  -washing powders - break down proteins, starch and fats in clothing. require alkaline pH to work effectively

  -food goes bad due to enzymes in bacteria breaking down organic matter. by stopping enzyme action, food can be preserved.

  e.g. pickling in vinegar / adding lemon juice to bananas